With the AppBuilder 3.0 release we introduced Gradle for all Android builds targeting Cordova 3.7+. As a consequence, the digit "2" is appended by Gradle to differentiate between different types of builds but could be counter intuitive. It is important to note that it happens within Cordova and there is an issue already logged about the behavior:
Apache Cordova CB-8976 platforms/android/build.gradle modifies android versionCode
Currently, we won't interfere with this behavior, as our modification could conflict with a solution Cordova comes up with. We plan to modify our resources to provide additional information about this specific in the build behavior though, as it may confuse other developers, too.
In case there are any other side effects from this change that you are concerned about, please let us know so that we can discuss this further.